| Résumé | We have studied the temperature dependence of resistivity, ρ, for a two-dimensional electron system in silicon at low electron densities ns∼1011 cm-2, near the metal-insulator transition. The resistivity was empirically found to scale with a single parameter T0, which approaches zero at some critical electron density nc and increases as a power T0∝‖ns-nc‖β with β=1.6±0.1 both in metallic (ns>nc) and insulating (ns<nc) regions. This dependence was found to be sample independent. We have also studied the diagonal resistivity at Landau-level filling factor ν=3/2, where the system is known to be in a true metallic state at high magnetic field and in an insulating state at low magnetic field. The temperature dependencies of resistivity at B=0 and ν=3/2 were found to be identical. These behaviors suggest a true metal-insulator transition in the two-dimensional electron system in silicon at B=0, in contrast with the well-known scaling theory. |
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